SignificanceDynamic phantoms capable of changing optical properties by control are essential for standardizing and calibrating spectroscopy systems such as the pulse oximeter. However, current liquid dynamic phantoms containing human blood have a short shelf life and require complex experimental setups. Some solid dynamic phantoms are influenced by the angular-dependent performance of the liquid crystal display (LCD), some have a low spatial resolution, and some have slow control of optical properties.AimWe aimed to develop a solid dynamic phantom, which can overcome these obstacles by changing the optical properties rapidly and generating dynamic biological signals.ApproachThe absorption properties of the phantom can be controlled in real time by modulating an LCD. A light guide was employed to avoid the angular-dependent performance of the LCD by isolating the scattering top-layer tissue-mimicking silicone phantom from the LCD.ResultsThe dynamic phantom was characterized at 940, 660, 530, and 455 nm to create a lookup table. Photoplethysmography signals of different heart rates from 80 to 120 beats per minute were synthesized, and oxygen saturation levels at 86%, 90%, 95%, and 100% were generated at multiple wavelengths.ConclusionsThe design, characterization, and potential applications of the dynamic phantom have been presented. This dynamic phantom can simulate various biological signals by applying corresponding modulation signals and has the potential to calibrate and validate pulse oximeter, imaging, and spectroscopy systems.
SignificancePhantoms play a critical role in the development of biophotonics techniques. There is a lack of novel phantom tools in the emerging field of upconverting nanoparticles (UCNPs) for biophotonics application. This work provides a range of UCNP-based phantom tools and a manufacturing recipe to bridge the gap and accelerate the development of UCNP-based biophotonics applications.AimThe study aims to provide a well-characterized UCNP-based solid phantom recipe and set of phantom tools to address a wide range of UCNP-based biophotonics applications.ApproachA solid phantom recipe based on silicone matrix was developed to manufacture UCNP-based phantoms. A lab built UCNP imaging system was used to characterize upconverted fluorescence emission of phantoms for linearity, homogeneity, and long-term stability. A photon time-of-flight spectroscopy technique was used to characterize the optical properties of the phantoms.ResultsIn total, 24 phantoms classified into 4 types, namely homogeneous, multilayer, inclusion, and base phantoms, were manufactured. The phantoms exhibit linear behavior over the dosage range of UCNPs. The phantoms were found to be stable over a limited observed period of 4 months with a coefficient of variation of < 4 % . The deep tissue imaging case showed that increasing the thickness of tissue reduced the UCNP emission.ConclusionsA first-of-its-kind UCNP-based solid phantom recipe was developed, and four types of UCNP phantom tools to explore biophotonics applications were presented. The UCNP phantoms exhibited a linear behavior with dosage and were stable over time. An example case showed the potential use of the phantom for deep tissue imaging applications. With recent advance in the use of UCNPs for biophotonics, we believe our recipe and tools will play a pivotal role in the growth of the UCNPs for biophotonics applications.
Phantoms play a critical role in the development of biophotonics techniques. There is currently a lack of solid phantoms relevant to the emerging field of upconverting nanoparticles (UCNP) for biophotonics application. This work intends to showcase a range of UCNP-based phantom models and manufacturing recipe to bridge the gap and accelerate the development of UCNP-based biophotonics applications. A total of 24 phantoms were classified into 4 different categories: homogeneous, multilayer, tumour inclusion and UCNP background phantoms were manufactured and an example use case was explored. The optical properties (absorption, reduced scattering and UCNP emission) of these phantoms were found to be stable over a period of 4 months with CV < 4%. With the recent advances in the use of UCNP for biophotonics, we believe our recipe and tools will play a pivotal role in the growth of the UCNP for biophotonics applications.
KEYWORDS: Monte Carlo methods, Diffuse optical tomography, Sensors, Near infrared spectroscopy, Spectroscopy, Oxygen, Injuries, Hybrid optics, Heart, Head
We present a simulation study on the design of a multi-modal high-density hybrid diffuse optical tomographic probe for monitoring infants with congenital heart disease (CHD) before, during, and after surgery. Different probe designs are evaluated based on the signal distribution and sensitivity profile generated using a Monte Carlo-based simulation toolbox. An optimal design was chosen after several iterations starting from the initial design. To cover a wide region of interest, this unit design was extended in a modular fashion, while respecting mechanical restrictions as well as the need for dense distribution of sources and detectors.
Endothelial dysfunction represents a key factor in the worsening of the COVID-19 disease in up to 20% of the cases of infection from acute respiratory distress syndrome coronavirus-2 (SARS-CoV-2). The combination of diffuse optics and vascular occlusion tests makes the assessment of endothelial and microvasculature health possible by accessing information about microvascular metabolism, reactivity and tissue perfusion just by performing a localized ischemia at the forearm of the patient. In this framework, we will present a smart platform integrating time-domain near-infrared spectroscopy and diffuse correlation spectroscopy alongside an automatized tourniquet and a pulse-oximeter for personalizing therapies targeting endothelial function and avoid ventilator-induced lung injuries.
We propose a standardized approach for performance assessment and quality-control of the novel VASCOVID system based on optical phantoms. This approach is tailored to meet the requirements of the Medical Device Regulation, and is extendable to other biophotonics devices.
The VASCOVID project aims to develop an hybrid diffuse optical device with a vascular occlusion protocol for evaluating endothelial and microvascular health in severe COVID-19 patients admitted to the ICU.
A standardized approach to develop a reliable, reproducible, stable phantoms was proposed. A well-established instrument validation protocol (MEDPHOT) was adopted for this purpose. This approach was tested on two phantom recipes (silicone and polyurethane) over broadband (600-1100 nm) wavelength covering a wider range of optical properties (absorption 0.1-1 cm-1, reduced scattering 5-20 cm-1) relevant to human tissue. As an application of the recipe, a reliable tissue-mimicking 3D anthropomorphic head phantom was presented.
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